This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 239 |
| 5 | 2902 |
| 6 | 44441 |
| 7 | 830636 |
| 8 | 18495910 |
| 9 | 481474188 |
| 10 | 14432543299 |
| 11 | 492063896964 |
| 12 | 18885525411110 |
| 13 | 808850019798316 |
| 14 | 38368738864146619 |
| 15 | 2002743853356179552 |
| 16 | 114374154959904537521 |
| 17 | 7110312727864509410026 |
| 18 | 479017371580348640009295 |